It would be desirable to commercially fill containers with base food products and toppings, where the topping is formed as a layer above the base food product which principally fills the container. In commercially filling containers with such composite food products, it is desirable to fill the container in a "single-pass" operation, i.e., in which the container is filled in a series of operations that are not interrupted for any undue length of time. In fact, food processing today is carried out in a "form, fill and seal" technique in which the container is formed from sheet stock material, the container is filled, and the filled container is sealed in one reasonably uninterrupted series of operations.
Certain food products have not been conducive to filling containers in a "single-pass" operation. Gellable food products, such as gelatin desserts and some cheeses and puddings, to name a few, require time for the product to gel set after it is placed in a container. Containers of these gellable food products have not, to my knowledge, been produced commercially with a separate layer or topping of another food product, especially with toppings having a higher specific gravity than the gellable base product. It is impractical from a commercial standpoint to partially fill a container with a gellable food product, and then apply a temporary lid or seal while the product gel-sets, after which the temporary lid or seal is removed and a topping is introduced to the container after the gel-set product has attained sufficient gel strength to support the topping. Such a "double-pass" process is not only too time consuming, but also presents a potential for contamination which can otherwise be avoided by a "single-pass" process. It is impractical from a commercial standpoint to fill containers with a gellable food product and attempt to place a topping on it before the base product gel sets, because in most cases it will not have the gel strength necessary to self-support the topping, especially a topping with a higher specific gravity. The topping will sink to the bottom of the container.
Hence, gellable food products with toppings are not common food items because the prior art has not provided a commercially practical method for filling containers with such products in a single-pass operation.
The food packaging industry has recognized the consumer's desire to be shown what they are buying; and this is accomplished by marketing food products in see-through containers, or at least in containers with a transparent see-through lid. Significantly, food products in containers with see-through lids are not visually attractive to the consumer if there is an air space or "head space" between the product and the inside of the see-through lid. However, it is difficult to conventionally fill a container with just the right amount of a food product and then place a lid on the container and have the product stay in contact with the lid, i.e., with no head space during prolonged storage.
Not only does the absence of head space make the food product more visually attractive through a see-through lid, but it also inhibits discoloration and flavor deterioration otherwise caused by oxygen in the air being entrapped between the product and the lid.
This invention overcomes the shortcomings of the prior art and provides a method for filling containers with a base food product and a topping in a single-pass operation, even though the topping may have a higher specific gravity than the base food product. The method facilitates maintaining the topping in constant contact with the inside surface of the lid, and therefore the product can have an attractive appearance to the consumer when packaged in a container with a see-through lid. Discoloration and flavor deterioration can also be inhibited.